1. Field of the Invention
The invention relates to a hinge for a portable computer, and in particular relates to a hinge for a portable computer requiring less torque to open and greater torque to close.
2. Description of the Related Art
Referring to FIG. 1, a portable computer has a monitor 32 and a base 31 connected by a hinge (not shown). The hinge allows the monitor 32 to rotate with respect to the base 31. Currently, the torque required for operating a hinge of a portable computer is constant. Operation of a conventional hinge is described via a torque curve in the following:
FIG. 2 depicts a torque curve of a hinge for a portable computer, wherein the hinge does not maintain the monitor in a closed position. Rather, the monitor is locked in the closed position via a latch (not shown). To open the monitor, the latch must be released. As shown in FIG. 2, the required torque T is a constant A1 as the monitor is opened (θ=0°−180°) and a constant “A” as the monitor is closed (θ=180°−0°), wherein A1=0.7A−0.75A.
FIG. 3 depicts a torque curve of another hinge for a portable computer, wherein the hinge is capable of maintaining the monitor in a closed position. In this case, no latch is provided for locking the monitor in the closed position. It is noted that the torque is not zero at θ=0° for the hinge to position the monitor. Furthermore, the required torque T remains constant through most of the process of operation. Specifically, the required torque T is a constant A1 during opening of the monitor (θ=15°−180°) and a constant “A” during closing of the monitor (θ=180°−15°). In FIG. 3, A0=1.2A.
Different designs may have different structural specifications for hinges, although the performance of hinges in portable computers is similar. Thus, only the torque curves of the hinges have been described and structural descriptions of the hinges have been omitted.
To meet design requirements, the battery in a typical portable computer is generally disposed at the rear of the base and near the hinge. The battery is a heavy element in the portable computer. Such an arrangement concentrates the weight of the portable computer at the rear. As a possible result, the base is raised when the monitor is opened. Alternatively, after the monitor is rotated to an angle, the base may accidentally fall and collide with a table or be raised along with rotation of the monitor. Thus, the monitor must be opened with both hands.